Description of Cetuximab (IMC-225) (Erbitux) (NSC-714692) Cetuximab, a chimerized antibody of the IgG1 subclass was originally derived from a mouse myeloma cell line. The chimerization resulted in an antibody with binding affinity to epidermal growth factor receptors (EGFR) greater than the natural ligand epidermal growth factor (EGF). Cetuximab blocks binding EGF and transforming growth factor (TGFa) to EGFR and inhibits ligand-induced activation of this tyrosine kinase receptor. Cetuximab also stimulates EGFR internalization, effectively removing the receptor from the cell surface for interaction with ligand.